Hello! You asked about the role of the supernatural in Things Fall Apart. Besides tribal belief in traditional Igbo gods and goddesses, there are also the otherworldly superstitions prevalent among Okwonko's people.
Traditional belief in gods and goddesses and their role:
1) For personal comfort.
Ikemefuna sings a song to comfort himself on (what he considers) his journey home. He is accompanied by Okwonko (whom he has come to consider a father) and the men of the village of Umuofia. Ikemefuna does not realize that he is marching to his death. The men plan to kill him to avenge the murder of Udo's wife. Along the way, Ikemefuna's thoughts are of his mother and his little sister. He worries whether his mother still lives. He sings a song from his childhood which used to comfort him in times of distress. It is a defense mechanism, sure, but he also derives great courage from it. He reasons that Chukwu, the Lord of Heaven, will hear his first voice and provide his heart's wishes.
2) For redress of grievances when all else fails.
Akunna argues with Mr. Brown, the white missionary, about little gods and the idea of an Overlord. Akunna insists that Chukwu has many servant gods for the people to appeal to. When all else fails, Chukwu is approached as the last source of hope. Mr. Brown disagrees and tries to tell Akunna that no one should be afraid of God the Father, and that all can approach him without fear. The Igbo people believe that when one has failed to perform Chukwu's will, one should be afraid of approaching him. Yet he is so great that Akunna wonders whether mere human beings will fully know his true will. Akunna's people believe that all is not lost when prayers are not immediately answered: Chukwu's majestic power reminds the Igbo that they are not without recourse when it comes to life's most pressing problems and that they have a sympathetic advocate through the hard trials of life.
3) For community stability and peace, a sense of tribal identity.
Personal gods like Ani, Amadiora, Idemili, Agbala, and Ogwugwu are a source of community stability and peace. They centralize in the collective consciousness that certain rituals and ceremonies are to be respected and adhered to; the prosperity of whole clans depends on adherence to certain principles. This contributes to a sense of belonging, a sense of community, and a sense of personal control over one's fate in life. Therefore, when a Christian convert in Mbanta boasts of killing a sacred royal python, the emanation of the god of water, all are aghast. The python is the most revered animal in Mbanta and all surrounding clans. Okwonko wants the Mbanta clan to kill the Christian converts. However, the clan leaders refuse; they argue that it is not their custom to fight for their gods. Okwonko accuses them of reasoning like cowards; he is disgusted by what he considers the womanly cowardice of the clan members.
Here, we can see the importance of Igbo traditional beliefs in the lives of the people. The influence of Christianity within the clans has contributed to the societal disintegration of the Igbo. The missionaries well-meaning desire to bring civilized worship and progressive ways to the Igbo people has instead led to confusion and despair among the Igbo. The missionaries did not take into consideration the depth of loyalty the Igbo have toward their gods, nor did they consider the Igbo dependence on tribal gods for tribal unity and identity.
Belief in the ogbanje: the ogbanje is an evil child who continually plagues a mother by entering her womb again and again to be birthed by her, only to die. In Things Fall Apart, Mr. Smith, the missionary, suspends a woman from the church for allowing her heathen husband to mutilate their child, whom they consider an ogbanje. Mutilation is believed to prevent the evil spirit from returning. An Ogbanje child is frequently sick, and many succumb to death. The ogbanje explanation serves to help grieving parents come to terms with the deaths of well-loved children.
The egwugwu, spirits of ancestors, are called on to solve quarrels or disagreements between clan members. The egwugwu are formidable spirits, often dressed in forbidding and majestic ceremonial dress. They instill terror in the hearts of the aggrieved party as well as the hearts of the perpetrators. All know that they are to be held to standards of justice that have served the clans for many ages. An example is when Uzowulu brings his case to the egwugwu. He claims that his wife's three brothers abused him physically, took her from their hut, and deprived him of her bride price. However, Mbagfo's three brothers accuse Uzowulu of being an abusive husband, causing Mbagfo to miscarry at least once. In the end, the egwugwu side with Mbagfo. The supernatural powers of the egwugwu are accepted without question; they serve to instill deep awe and respect among those who come to them for help.
I hope this provides a framework for you to work with. Thanks for the question. Very interesting query!
For further study and research, I would like to draw your attention to the following links:
All three links will definitely lead you to further understanding and compassion for the role of the supernatural in the lives of the Igbo. The British and their missionaries very much desired to bring a better world to the Igbo; however, as I mentioned above, they greatly underestimated the dependence of grieving parents upon long-held sacred rituals which provided comfort and strength. Once again, really interesting topic!